What Is the ABN (CMS-R-131)?

The Advance Beneficiary Notice of Noncoverage (ABN), CMS-R-131, is a standardized notice issued to Original Medicare (fee-for-service) beneficiaries when a provider believes Medicare is likely to deny payment for a specific item or service. The form allows the beneficiary to make an informed decision about whether to receive the service and accept potential financial responsibility.

The ABN was first approved by the Office of Management and Budget on March 1, 2011 (OMB Control Number 0938-0566) and remains a core compliance requirement for providers billing Original Medicare. CMS continues to maintain and periodically update ABN guidance through the Beneficiary Notices Initiative to reflect coverage rules, documentation standards, and audit expectations.

An ABN must be issued before the service is furnished, and only when a denial is reasonably expected under Medicare coverage rules. It does not apply to Medicare Advantage plans, Medicaid, or commercial payers, and it cannot be used retroactively after a claim has already been submitted or denied.

When an ABN Is Required

ABNs are most commonly used when services are expected to be denied due to medical necessity, frequency limitations, or statutory exclusions. Typical scenarios include services that exceed Medicare’s coverage limits, screenings performed more frequently than allowed, or treatments that do not meet Medicare’s medical necessity criteria. CMS guidance remains clear that ABNs may not be issued routinely or as a blanket practice. Providers must have a specific, defensible reason to believe Medicare will deny payment for the individual service in question. Improper or overuse of ABNs can itself create compliance exposure during audits or investigations.

Correct Coding and Billing to Avoid Compliance Risk

When a provider elects to shift financial responsibility to the beneficiary using an ABN, coding accuracy becomes especially critical. Even if Medicare is expected to deny the claim, the codes submitted must accurately reflect the services rendered and mirror what would have been billed to Medicare absent the anticipated denial.

The diagnosis, procedure, and modifier combinations must remain clinically and technically correct. Substituting alternative codes, simplifying documentation, or altering claim structure when billing the beneficiary can expose providers to allegations of improper billing or misrepresentation. CMS and Medicare Administrative Contractors routinely review ABN-related claims to ensure consistency among clinical documentation, coding, and beneficiary billing. Proper use of modifiers—such as those indicating statutorily noncovered services or expected denials—remains essential. Incorrect modifier usage is a frequent audit finding and can invalidate an otherwise valid ABN.

Recent Compliance Emphasis and Ongoing Updates

In recent years, CMS audit activity has continued to focus on beneficiary notice compliance, particularly in outpatient, diagnostic, and ancillary service settings. Improper ABN issuance, missing signatures, vague service descriptions, and unsupported expectations of denial remain common areas of risk. CMS has also reinforced expectations around documentation retention and audit readiness. Providers are expected to maintain completed ABNs, supporting medical records, and evidence that the notice was adequately explained to the beneficiary before service delivery. As enforcement efforts increasingly rely on data analytics, inconsistent ABN usage patterns can draw additional scrutiny.

Why ABN Accuracy Matters

The ABN is not merely a financial notice; it is a compliance safeguard. When used correctly, it protects beneficiaries from unexpected bills and providers from inappropriate write-offs or recoupments. When used incorrectly, it can trigger claim denials, refunds, civil monetary penalties, or broader compliance reviews.

Ensuring accurate coding, consistent billing practices, and defensible documentation remains the most effective way to reduce ABN-related risk. As Medicare coverage rules evolve and audit sophistication increases, ABN compliance continues to require careful operational oversight rather than administrative routine.

Summary of ABN CMS R131

The ABN (CMS-R-131) remains a critical compliance tool for providers billing Original Medicare, but its effectiveness depends entirely on proper use, accurate coding, and defensible documentation. As CMS continues to emphasize beneficiary notice integrity through audits and data-driven oversight, routine or inconsistent ABN practices create unnecessary risk. Providers that treat the ABN as a formal compliance safeguard—rather than a billing workaround—are better positioned to protect beneficiaries, withstand audits, and avoid recoupments tied to improper notice issuance or inaccurate claims submission.